Print

Easy Confetti Birthday Sheet Cake with Buttercream

confetti birthday sheet cake - featured image
Print Recipe

A tender, buttermilk-based sheet cake studded with rainbow sprinkles and topped with silky buttercream frosting. Perfect for last-minute birthday celebrations or any day that needs a little extra joy.

Ingredients

Scale
  • 1 cup (2 sticks / 227g) unsalted butter, softened
  • 2 cups (400g) granulated sugar
  • 4 large eggs, room temperature
  • 1 ½ cups (360ml) buttermilk, room temperature
  • 2 teaspoons pure vanilla extract
  • 3 cups (360g) all-purpose flour, spooned and leveled
  • 2 teaspoons baking powder
  • ½ teaspoon baking soda
  • 1 teaspoon fine sea salt
  • ½ cup (90g) rainbow jimmies sprinkles
  • 1 ½ cups (3 sticks / 340g) unsalted butter, softened (for frosting)
  • 4 cups (480g) powdered sugar, sifted
  • 3–4 tablespoons (45–60ml) heavy cream
  • 2 teaspoons pure vanilla extract (for frosting)
  • a pinch of salt (for frosting)
  • ¼ cup (45g) extra rainbow jimmies for decorating

Instructions

  1. Preheat oven to 350°F (175°C). Grease a 13×9-inch baking pan and line with parchment paper, leaving overhang on the long sides.
  2. In a medium bowl, whisk together 3 cups flour, 2 teaspoons baking powder, ½ teaspoon baking soda, and 1 teaspoon salt. Set aside.
  3. In a large bowl, beat 1 cup softened butter with 2 cups granulated sugar on medium speed for 3–4 minutes until light and fluffy. Scrape down sides.
  4. Add eggs one at a time, beating well after each addition (about 30 seconds per egg).
  5. Mix in 2 teaspoons vanilla and 1 ½ cups buttermilk on low speed until just combined. Batter may look slightly curdled.
  6. With mixer on low, add half the flour mixture, mixing until just a few streaks remain. Add remaining flour and mix until combined. Do not overmix.
  7. Gently fold in ½ cup rainbow jimmies using a rubber spatula with slow, sweeping motions.
  8. Pour batter into prepared pan and spread evenly. Tap pan gently on counter to release air bubbles.
  9. Bake for 28–32 minutes, until a toothpick inserted in center comes out clean or with a few moist crumbs. Cool in pan for 10 minutes, then transfer to wire rack to cool completely (about 1 hour).
  10. For buttercream: In a large bowl, beat 1 ½ cups softened butter on medium-high speed for 5 minutes until pale and fluffy.
  11. Gradually add 4 cups powdered sugar on low speed, about 1 cup at a time. Mixture will look dry and crumbly.
  12. Add 3 tablespoons heavy cream, 2 teaspoons vanilla, and a pinch of salt. Beat on medium speed for 3–4 minutes until smooth and spreadable. Add remaining tablespoon of cream if too thick.
  13. Frost cooled cake with offset spatula, spreading buttercream evenly to edges. Top with extra sprinkles.

Notes

Use jimmies sprinkles, not nonpareils, to prevent color bleeding. Room temperature ingredients are crucial for proper emulsification. Cake can be made a day ahead; flavors develop overnight. Store unfrosted cake tightly wrapped at room temperature for up to 3 days. Freeze unfrosted cake for up to 3 months.

Nutrition

Keywords: birthday cake, confetti cake, sheet cake, buttercream, sprinkles, easy cake, party cake

Find it online: https://eliplate.com/easy-confetti-birthday-sheet-cake-with-buttercream/